POSIX abstractions in modern operating systems: the old, the new, and the missing

The POSIX standard, developed 25 years ago, comprises a set of operating system (OS) abstractions that aid application portability across UNIX-based OSes. While OSes and applications have evolved tremendously over the last 25 years, POSIX, and the basic set of abstractions it provides, has remained largely unchanged. Little has been done to measure how and to what extent traditional POSIX abstractions are being used in modern OSes, and whether new abstractions are taking form, dethroning traditional ones. We explore these questions through a study of POSIX usage in modern desktop and mobile OSes: Android, OS X, and Ubuntu. Our results show that new abstractions are taking form, replacing several prominent traditional abstractions in POSIX. While the changes are driven by common needs and are conceptually similar across the three OSes, they are not converging on any new standard, increasing fragmentation.